The present invention relates to apparatus for detecting and indicating the signs of a fire such as smoke or heat so as to provide warning of the probability or possibility of fire.
Known fire detecting systems of the prior art have many disadvantages. They are normally rigidly or fixedly installed in locations where it is desired to monitor the presence of smoke or heat. They are usually dependent upon the building electrical system which may be rendered inoperative itself in the event of a fire. The alarm indicators themselves are usually placed at some distance from the smoke or heat detector itself where it could be difficult for a person having hearing or visual problems to be alerted. Further, they cannot be conveniently tested by the individuals they are designed to protect and warn. In some earlier apartment units where smoke or heat detectors are not located, the apartment dwellers themselves may not be allowed to mount heat or smoke alarms on ceilings due to radiant heating coils in the ceiling. Where prior art systems do exist, they are usually very expensive and link together one system for an entire building.
Further, it is important to be able to detect a fire at different locations in a building depending upon times or seasons. For instance, in the winter when the furnace is running a great amount of time, it is important to be alert for fires in the furnace area. In the summer when the air conditioning units have predominant use, it may be important to check these units for overheating. In the summer, it would be advantageous to locate a heat sensor somewhere other than near a window. In the winter, it would be appropriate to locate a sensor near the fireplace to detect overheating or smoke entering the room.
Also, it is important to be able to locate a fire sensor at different heights in a room. In the summer when the heat rises, it is important to locate a heat sensor somewhere other than near the ceiling. In the winter, the sensor may be more advantageously located near the ceiling. Where there are heating ducts near the floor, it may be desired to locate the sensor near the floor; where the heating ducts are located near the ceiling, it would be appropriate and desirable to locate the sensor near the ceiling. Obviously, "hot spots" or areas susceptible to fire can be located almost anywhere in a building.
Thus, the need is to be able to have an economical yet reliable fire detection system which is portable and yet can have a sensor easily selectively positionable where needed. A sensor can be so positioned if mounted at the outermost end of an extensible rod or column such as an antenna which is both pivotably and rotatably attached at its base to a fixture and which has a maximum and a minimum extended length. The sensor can then be positioned anywhere within a hemisphere of revolution generated by sweeping said extensible antenna through 360' of rotation about its pivot point while moving from a vertical position to a horizontal position, the maximum radius of said hemisphere of revolution being equal to the fully extended length of the extensible antenna and the minimum radius of said hemisphere of revolution being equal to the shortest collapsed length of the extensible antenna.